aspm - get current state? difference between "performance" and "off"?
Hi
On a running system how can I know current (active) ASPM policy?
I've tried this command and so think that ASPM is disabled on my system, am I correct? What is right way to check ASPM status?
[root@localhost]# lspci -vv | grep ASPM
LnkCap: Port #0, Speed 2.5GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #8, Speed 8GT/s, Width x8, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #16, Speed 8GT/s, Width x8, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk+
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #18, Speed 8GT/s, Width x8, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #24, Speed 8GT/s, Width x16, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk+
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #17, Speed 2.5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <64ns, L1 <1us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled+ CommClk-
LnkCap: Port #1, Speed 5GT/s, Width x4, ASPM L0s L1, Exit Latency L0s <1us, L1 <4us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #8, Speed 5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <1us, L1 <4us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 2.5GT/s, Width x1, ASPM L0s, Exit Latency L0s <4us, L1 <4us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 2.5GT/s, Width x1, ASPM L0s, Exit Latency L0s <4us, L1 <4us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 2.5GT/s, Width x1, ASPM L0s, Exit Latency L0s <4us, L1 <4us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 2.5GT/s, Width x1, ASPM L0s, Exit Latency L0s <4us, L1 <4us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 8GT/s, Width x8, ASPM not supported, Exit Latency L0s unlimited, L1 <64us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 5GT/s, Width x4, ASPM L0s L1, Exit Latency L0s <1us, L1 <2us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk+
LnkCap: Port #0, Speed 5GT/s, Width x4, ASPM L0s L1, Exit Latency L0s <1us, L1 <2us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk+
LnkCap: Port #0, Speed 5GT/s, Width x4, ASPM L0s L1, Exit Latency L0s <1us, L1 <2us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk+
LnkCap: Port #0, Speed 5GT/s, Width x4, ASPM L0s L1, Exit Latency L0s <1us, L1 <2us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk+
LnkCap: Port #0, Speed 8GT/s, Width x8, ASPM L0s L1, Exit Latency L0s unlimited, L1 <64us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk+
LnkCap: Port #0, Speed 8GT/s, Width x8, ASPM L0s L1, Exit Latency L0s unlimited, L1 <64us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk+
LnkCap: Port #0, Speed 2.5GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
LnkCap: Port #0, Speed 8GT/s, Width x4, ASPM L1, Exit Latency L0s unlimited, L1 <16us
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
From documentation:
performance - disables ASPM to allow PCIe links to operate with maximum performance.
What is the differenct between "pcie_aspm=off" and "pcie_aspm .policy=performance". Is it the same?
Thanks,
Oleg
Responses
Hi Oleg,
I need to confirm the behaviour with the engineer responsible here. In short, as we understand the code there is a difference in behaviour between the two options, but we want to confirm exactly what that is before we respond.
I will get a definitive update to you a little later (the engineer is in another TZ)
Mark
Hi Oleg,
Apologies for the delay, but I have a definitive answer for you.
pci_aspm=offmeans the kernel won't touch the ASPM registers- This means it will leave whatever the platform's BIOS put in place there, which at a hardware level, could include devices having ASPM on. This may be desirable in some circumstances
policy-performancemeans the kernel will reprogram the ASPM registers to disable it
Best regards,
Mark
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